1. Field of the Invention
The present invention relates to an improvement on an information reproducing apparatus and a camera, for reproducing information recorded on a recording medium.
2. Description of Related Art
Cameras adapted for use of film cartridges of a type called IX240 are called APS cameras. It is well known that the cameras of this kind permit recording on the film some information about photo-taking conditions, dates, etc., by magnetic means or some other suitable means, so that information related to the photo-taking operation is recorded on a recording part corresponding to the exposed frame. Many of these cameras are arranged to have a so-called film midway loading function (hereinafter referred to as the MRC function). This MRC function permits use of a partially used (exposed) film by reloading the film in a state of having some frames left unexposed and by automatically setting each of the unexposed frame at a photo-taking aperture position.
The MRC function is generally performed in the following manner. When the camera is loaded with a partially used film, the camera reads magnetic information recorded at frames already exposed. Any frame having no magnetic information recorded there is recognized as an unexposed frame. Then, one of the unexposed frames is set to be used as a leading frame for photo-taking after reloading.
In carrying out the MRC function, if a magnetic information reproducing system disposed within the camera is affected by some external noise or the like, it is highly probable that the camera might mistake an unexposed frame for an exposed frame. To solve this problem, a filter passing frequency band of the magnetic information reproducing system is generally set at a narrow bandwidth to make the system not readily affected by the external noise or the like. This arrangement enables the camera to be capable of correctly recognizing the presence or absence of magnetic information. Hereinafter, this arrangement will be called a first prior art example.
The camera having the MRC function has another problem in respect of use of the MRC function. In a case where there are many partially used films, contents of records on the films are extremely difficult to manage. According to a method developed for solving that problem, magnetic information recorded at each of exposed frames, such as a title and photo-taking conditions, is read in transporting the film after the film is reloaded. Then, some representative data among the contents of the information read, such as data recorded at the last exposed frame, is displayed to let the user easily know contents of records. Hereinafter, that method will be called a second prior art example.
In the case of the second prior art example, the magnetic reproduced signal must be accurately read as data. To meet this requirement, the filter passing band must be arranged to be as wide as possible. It is also necessary that the rate of amplifying the reproduced signal must be suppressed to be relatively low, i.e., to a degree at which the reproduced signal does not saturate. The arrangement for making such setting makes it possible to let the user know information recorded on the film even in a case where a film taken out from the camera is reloaded to be used again. Therefore, the seriousness of the problems of the MRC function can be mitigated.
However, as a result of popularization of the cameras of the kind having the MRC function, there arises a case where one and the same film is desired to be used by a plurality of (two, for example) cameras. In such a case, however, even a slight difference in structural arrangement between the two cameras might bring about another problem. For example, with a film which is used for photo-taking only in part by one camera is loaded on another camera, an azimuth deviation of an information reproducing head (a difference in reading angle) might prevent the second camera from adequately reading the magnetic information. Then, xe2x80x9cthe exposed frame showing informationxe2x80x9d of the second prior art example or, in the worst case, xe2x80x9cthe leading unexposed frame recognizing actionxe2x80x9d of the first prior art example might become erroneous. In the event of such an error, the camera might fail to recognize the presence of a magnetic signal record or might make a double exposure to give overlapped pictures or the like.
FIGS. 16(a) and 16(b) show a difference in reproduced signal waveform between a case where the information reproducing head does not deviate in azimuth and another case where the information reproducing head deviates in azimuth by xe2x88x921xc2x0.
Each of signals shown in FIGS. 16(a) and 16(b) has a voltage value of about 2 V at the center of the waveform. The signal includes a clock signal which serves as reference for every bit of information and drops from around the center voltage of 2 V, and data obtained for the clock signal rises from the center voltage of 2 V. The signal is recognized as xe2x80x9c0xe2x80x9d if the data is located on the left side of a 50% position with respect to the clock signal and as xe2x80x9c1xe2x80x9d if the data is on the right side of a 50% position with respect to the clock signal. Although the data is determined with a 50% position with respect to the clock signal set as the boundary, in order to lessen errors in making a discrimination between xe2x80x9c0xe2x80x9d and xe2x80x9c1xe2x80x9d, the data is recorded, as a basic rule, to have the data xe2x80x9c0xe2x80x9d as close to a 30% position with respect the clock signal as possible and the data xe2x80x9c1xe2x80x9d as close to a 70% position with respect to the clock signal as possible. All the data used for reproduction shown in FIGS. 16(a)and 16(b)are assumed to have been recorded with data xe2x80x9c0xe2x80x9d.
The reproduced waveform shown in FIG. 16(a)is obtained by reproducing data from a film with a reproducing head set at the same azimuth angle as a recording head used in recording the data on the above-stated condition. The signal amplitude is large (Vp xe2x88x92p≈2.2 V). This waveform permits accurate recognition of that the data is around 30%. In the case of FIG. 16(b), the reproduced waveform is obtained from the same film with a reproducing head set at a position which deviates about one degree from the azimuth angle of the recording head. Although the waveform is obtained from the same film, the signal amplitude of FIG. 16(b)is small (Vp xe2x88x92P≈1.4 V). The small amplitudes not only makes signal recognition difficult but also is apt to mislead the discrimination to be made between xe2x80x9c0xe2x80x9d and xe2x80x9c1xe2x80x9d of data.
The above-stated problem can be solved by providing the camera with some angle adjustment mechanism for adjusting the azimuth angle of a magnetic reproducing head while observing the signal level in process of a magnetic signal reproduction. However, such a method necessitates use of a complex mechanism, which is hardly adoptable for cameras which must meet the requirement of these days for reduction in size and cost.
The invention is directed to the solution of the problems of the prior art described in the foregoing. In accordance with one aspect of the invention, there is provided an information reproducing apparatus or a camera arranged to be not only capable of making an accurate discrimination between the presence and absence of information, without being affected by noises, but also capable of lessening the possibility of errors in reproducing information.
In accordance with one aspect of the invention, there is provided a camera arranged to be not only capable of accurately setting the position of a leading frame among unexposed frames without being affected by noises but also capable of lessening errors in reproducing information.
In accordance with one aspect of the invention, there is provided a camera arranged to sufficiently have minimum necessary functions as a camera of the kind having a film midway loading (MRC) function and not only to enhance the accuracy of reproduction of information recorded on a film with which the camera is loaded but also to appositely provide the user of the camera with information relative to a film reloaded on the camera.
In accordance with one aspect of the invention, there is provided an information reproducing apparatus of the kind having reproducing means for reproducing information recorded on a recording medium and noise removing filter means which permits switch-over of its passband from one passband to another. The information reproducing apparatus is provided with passband switch-over means which is arranged to switch the passband of the filter means from one passband over to another according to whether the filter means is to be used for making a discrimination, by the reproducing means, between the presence and absence of information recorded on the recording medium or to be used for decoding the information recorded on the recording medium.
In accordance with one aspect of the invention, there is provided a camera having reproducing means for reproducing information recorded in an information recording area of a film and noise removing filter means which permits switch-over of its passband from one band to another. The camera is provided with passband switch-over (or varying) means which is arranged to switch the passband of the filter means from one passband over to another according to whether the filter means is to be used for an action of making a discrimination, by the reproducing means, between the presence and absence of information recorded on the film or to be used for decoding the information recorded in the information recording area.
In accordance with one aspect of the invention, there is provided a camera having reproducing means for reproducing information recorded in a recording area of a film, noise removing filter means which permits switch-over of its passband from one passband to another, and a film midway loading function. The camera having the film midway loading function is provided with the passband switch-over means which is arranged to switch the passband of the filter means from one passband over to another according to whether the filter means is to be used for an action of deciding a leading frame among unexposed frames on the basis of the result of a discrimination made by the reproducing means between the presence and absence of information recorded in the recording area of the film or to be used for a decoding action of the reproducing means on the information obtained from the recording area after the deciding action.
In accordance with one aspect of the invention, there is provided an information reproducing apparatus having reproducing means for reproducing information recorded on a recording medium. The information reproducing apparatus is provided with level deciding means for deciding whether the level of a reproduced signal is higher than a predetermined level or not, and information recognizing action switch-over means for changing the process of a recognizing action on the information recorded on the recording medium according to the result of decision made by the level deciding means.
In accordance with one aspect of the invention, there is provided a camera having reproducing means for reproducing information recorded at a magnetic recording part of a film. The camera is provided with level deciding means for deciding whether the level of a reproduced signal is higher than a predetermined level or not, and information recognizing action switch-over means for changing the process of a recognizing action on the information recorded on the film according to the result of decision made by the level deciding means.